1. Field of the Invention
This invention relates to a seat cushion for use in a vehicle and a method of making the same. More particularly, this invention relates to a vehicle's seat cushion in which the damping characteristic of metal springs is improved, and the state of intimate contact between the metal springs and a block of foamed polyurethane is also improved, so that occupants of the vehicle can feel comfortable to sit on the seats.
2. Description of the Prior Art
A prior art seat cushion for a vehicle will be described with reference to FIGS. 8 and 9, before describing the present invention.
A prior art seat cushion made of foamed polyurethane has a peculiar deflection characteristic as shown in FIG. 8. In FIG. 8, the solid curve and broken curve represent the deflection characteristic of a metal spring and that of foamed polyurethane respectively.
The deflection characteristic of the seat cushion represented by the broken curve is not necessarily satisfactory from the viewpoint of giving a comfortable feeling of sitting. Therefore the elasticity of high elasticity foamed polyurethane is now utilized to compensate the insufficient deflection characteristic of the prior art seat cushion thereby improving the feeling of sitting. However, this effort has not been successful in improving the insufficient deflection characteristic of the prior art seat cushion.
FIG. 9 shows coiled metal spring members 1 assembled according to a prior art practice. The assembling of these spring members 1 has required an extra step resulting in incurrence of an additional cost since many clips (as shown by a numeral 5 in FIG. 6) are used to fasten the spring members 1 to, for example, an upper border wire (not shown). Further, because the spring members 1 shown in FIG. 9 are in contact with each other, rubbing engagement of these spring members with each other at their contact portions generates noise which cannot be eliminated even when a soundproof paint is coated on the spring members.